Brazing filler metal for connecting silicon carbide, preparation method of brazing filler metal and connecting method of silicon carbide

Abstract

The invention provides brazing filler metal for connecting silicon carbide, a preparation method of the brazing filler metal and a connecting method of the silicon carbide, and relates to the technical field of welding, the prepared brazing filler metal is ternary alloy silicon-based brazing filler metal composed of yttrium, titanium, praseodymium and silicon, the content of the silicon element in the ternary alloy silicon-based brazing filler metal is high (about 83%), so that the brazing filler metal has the low thermal expansion coefficient, and the service life of the brazing filler metal is prolonged. The thermal expansion coefficient can be well matched with the thermal expansion coefficient of silicon carbide. However, when the content of the silicon element in the brazing filler metal is high, the melting point of the brazing filler metal is high, and therefore metal yttrium and metal praseodymium are further introduced into the brazing filler metal, and the brazing filler metal has the low melting point. In addition, due to the fact that the metal praseodymium has high oxidation resistance, the oxidation resistance of the brazing filler metal can be remarkably improved by introducing the metal praseodymium into the brazing filler metal. In conclusion, the brazing filler metal prepared through the method has the low thermal expansion coefficient, the low melting point and the high oxidation resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of welding, and in particular to a brazing filler metal for silicon carbide connection and a preparation method thereof, and a silicon carbide connection method. Background Art

[0002] Silicon carbide is a material with high thermal conductivity, high wear resistance, high hardness, high chemical stability and excellent electrical properties, and is widely used in the field of semiconductor technology. However, the high hardness of silicon carbide itself limits its processing applications, especially some large or complex components. Welding has become an effective way to solve this technical problem. Compared with welding methods such as diffusion welding, brazing has the advantages of simple process, high production efficiency, and can be achieved at a lower temperature. However, at present, the thermal expansion coefficient of silicon carbide ceramics is relatively low (4.4×10 -6 K -1 ), the thermal expansion coefficient of commonly used metal-based solder is relatively large, which is quite different from that of silicon carbide ceramics. During the welding process, large thermal stress will be generated, which will affect the strength of the welded joint. In order to reduce the welding temperature of brazing, the solder needs to have a lower melting point. In addition, in order to ensure the service life of the device, the welded joint needs to have a high oxidation resistance, so the solder is required to have a high oxidation resistance. Summary of the invention

[0003] The problem solved by the invention is how to obtain a solder with a lower thermal expansion coefficient, a lower melting point and a higher oxidation resistance.

[0004] In order to solve the above problems, the present invention provides a method for preparing a brazing material for silicon carbide connection, comprising:

[0005] Step S1, smelting silicon, metal yttrium, metal titanium and metal praseodymium as raw materials to obtain a Si-Y-Ti-Pr brazing ingot; the mass ratio of yttrium element, titanium element, praseodymium element and silicon element in the Si-Y-Ti-Pr brazing ingot is (5.4 to 5.5): (5.4 to 5.5): (5.4 to 5.5): (83.5 to 83.6);

[0006] Step S2: Processing the Si-Y-Ti-Pr solder ingot into powder or flake form to obtain a solder for silicon carbide connection.

[0007] Compared with the related art, the solder prepared by the present invention is a ternary alloy silicon-based solder composed of yttrium, titanium, praseodymium and silicon. The content of silicon in the ternary alloy silicon-based solder is relatively high (about 83%), so that the solder has a lower thermal expansion coefficient and can better match the thermal expansion coefficient of silicon carbide. However, when the silicon content in the solder is relatively high, the melting point of the solder will be relatively high. Therefore, the present invention further introduces metal yttrium and metal praseodymium into the solder, so that the solder has a lower melting point. In addition, since metal praseodymium has a high antioxidant property, its introduction into the solder can significantly improve the antioxidant property of the solder. In summary, the solder prepared by the present invention has a lower thermal expansion coefficient, a lower melting point and a higher antioxidant property.

[0008] Optionally, in step S1, the mass ratio of yttrium, titanium, praseodymium and silicon in the Si-Y-Ti-Pr brazing ingot is 5.44:5.44:5.44:83.57.

[0009] Optionally, in step S1, the smelting is performed in a vacuum or protective atmosphere, the current during the smelting process is 200A, and the voltage is 30V to 45V.

[0010] Optionally, in step S1, the smelting time is 15s to 30s.

[0011] The present invention also provides a silicon carbide connecting brazing material, which is prepared by the method for preparing the silicon carbide connecting brazing material as described above.

[0012] The present invention also provides a method for connecting silicon carbide, comprising:

[0013] Step M1, placing the silicon carbide connection brazing material as described above between two silicon carbide parts to be connected to form a sandwich structure of the components to be connected;

[0014] Step M2: Under vacuum conditions, the components to be connected are heated to 1260° C. to 1280° C., and sintered at 1260° C. to 1280° C. to obtain silicon carbide connectors.

[0015] Compared with the related art, the solder used in the present invention for silicon carbide connection has a lower thermal expansion coefficient, which can better match the thermal expansion coefficient of silicon carbide, which is beneficial to reduce the thermal stress generated during the welding process, thereby ensuring that the welded joint of the silicon carbide connector has a higher strength. Since the solder has a lower melting point, the connection of silicon carbide can be achieved at a relatively low temperature (1260°C to 1280°C), thereby effectively preventing the adverse effects of excessive welding temperature on the silicon carbide base material. Since the solder has a higher oxidation resistance, the welded joint of the silicon carbide connector has a higher oxidation resistance. In addition, when the solder is used for silicon carbide connection, a diffusion layer will be formed between silicon carbide and the solder, which is beneficial to further improve the strength of the welded joint of the silicon carbide connector. In summary, the method of the present invention can be used to obtain a silicon carbide connector at a lower temperature, and the welded joint of the silicon carbide connector has higher strength and oxidation resistance.

[0016] Optionally, in the step M1, the silicon carbide connection brazing material is in the form of a sheet.

[0017] Optionally, the thickness of the silicon carbide connection brazing material in the components to be connected is 0.5 mm to 1 mm.

[0018] Optionally, in step M2, heating the components to be connected to 1260°C to 1280°C includes: heating the components to be connected to 800°C at a heating rate of 10°C / min to 20°C / min, keeping the temperature for 10 minutes, and heating the components to 1260°C to 1280°C at a heating rate of 5°C / min to 10°C / min.

[0019] Optionally, in step M2, the sintering treatment time is 10 minutes to 30 minutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The scanning electron microscope image of the solder prepared in Example 1 is taken;

[0021] Figure 2 This is an energy spectrum analysis picture of the solder prepared in Example 1;

[0022] Figure 3 This is a scanning electron microscope image of the weld of the silicon carbide connector prepared in Application Example 1;

[0023] Figure 4 This is a scanning electron microscope image of the weld of the silicon carbide connector prepared in Application Example 2;

[0024] Figure 5 This is a scanning electron microscope image of the weld of the silicon carbide connector prepared in Application Example 1 after being kept at 800°C in an atmosphere for 10 hours;

[0025] Figure 6 This is the energy spectrum analysis diagram of the weld of the silicon carbide connecting piece prepared in Application Example 1 after being kept at 800°C in an atmosphere for 10 hours. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] The term "including" and its variations used in this article are open inclusions, that is, "including but not limited to"; the term "based on" is "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0029] In view of the problems existing in the above-mentioned related technologies, this embodiment provides a method for preparing a brazing material for silicon connection, comprising:

[0030] Step S1, smelting silicon, metal yttrium, metal titanium and metal praseodymium as raw materials to obtain a Si-Y-Ti-Pr brazing ingot; the mass ratio of yttrium element, titanium element, praseodymium element and silicon element in the Si-Y-Ti-Pr brazing ingot is (5.4 to 5.5): (5.4 to 5.5): (5.4 to 5.5): (83.5 to 83.6);

[0031] Step S2: Processing the Si-Y-Ti-Pr solder ingot into powder or flake form to obtain a solder for silicon carbide connection.

[0032] The solder prepared in the embodiment of the present invention is a ternary alloy silicon-based solder composed of yttrium, titanium, praseodymium, and silicon. The content of silicon in the ternary alloy silicon-based solder is relatively high (about 83%), so that the solder has a lower thermal expansion coefficient and can better match the thermal expansion coefficient of silicon carbide. However, when the silicon content in the solder is relatively high, the melting point of the solder will be relatively high. Therefore, this embodiment further introduces metal yttrium and metal praseodymium into the solder, so that the solder has a lower melting point. In addition, since metal praseodymium has a high antioxidant property, its introduction into the solder can significantly improve the antioxidant property of the solder. In summary, the solder prepared in this embodiment has a lower thermal expansion coefficient, a lower melting point, and a higher antioxidant property.

[0033] In some embodiments of the present invention, preferably, in step S1, the mass ratio of yttrium, titanium, praseodymium and silicon in the Si-Y-Ti-Pr brazing ingot is 5.44:5.44:5.44:83.57.

[0034] In some embodiments of the present invention, exemplarily, in the step S1, the smelting is performed in a vacuum or protective atmosphere, the current during the smelting process is 200A, and the voltage is 30V to 45V.

[0035] In some embodiments of the present invention, in the step S1, the smelting time is 15s to 30s.

[0036] The embodiment of the present invention further provides a silicon carbide connection brazing material, which is prepared by the preparation method of the silicon carbide connection brazing material as described above.

[0037] An embodiment of the present invention further provides a method for connecting silicon carbide, comprising:

[0038] Step M1, placing the silicon carbide connection brazing material as described above between two silicon carbide parts to be connected to form a sandwich structure of the components to be connected;

[0039] Step M2: Under vacuum conditions, the components to be connected are heated to 1260° C. to 1280° C., and sintered at 1260° C. to 1280° C. to obtain silicon carbide connectors.

[0040] The solder used in the embodiment of the present invention when connecting silicon carbide has a low thermal expansion coefficient, which can be well matched with the thermal expansion coefficient of silicon carbide, which is conducive to reducing the thermal stress generated during the welding process, thereby ensuring that the welded joint of the silicon carbide connector has a high strength. Since the solder has a low melting point, the connection of silicon carbide can be achieved at a relatively low temperature (1260°C to 1280°C), thereby effectively preventing the adverse effects of excessive welding temperature on the silicon carbide base material. Since the solder has a high oxidation resistance, the welded joint of the silicon carbide connector has a high oxidation resistance. In addition, when the solder is used for silicon carbide connection, a diffusion layer will be formed between silicon carbide and the solder, which is conducive to further improving the strength of the welded joint of the silicon carbide connector. In summary, the method of this embodiment can be used to obtain a silicon carbide connector at a lower temperature, and the welded joint of the silicon carbide connector has high strength and oxidation resistance.

[0041] In some embodiments of the present invention, in the step M1, the silicon carbide connection brazing material is in the form of a sheet.

[0042] In some embodiments of the present invention, the thickness of the silicon carbide connection brazing material in the components to be connected is 0.5 mm to 1 mm.

[0043] In some embodiments of the present invention, in step M2, heating the components to be connected to 1260°C to 1280°C includes: heating the components to be connected to 800°C at a heating rate of 10°C / min to 20°C / min, keeping the temperature for 10 minutes, and heating the components to be connected to 1260°C to 1280°C at a heating rate of 5°C / min to 10°C / min.

[0044] In some embodiments of the present invention, in the step M2, the sintering treatment time is 10 minutes to 30 minutes.

[0045] The present invention is further described below in conjunction with specific embodiments.

[0046] Example 1

[0047] Silicon, metallic yttrium, metallic titanium and metallic praseodymium are used as raw materials for smelting to obtain a Si-Y-Ti-Pr brazing ingot; wherein the smelting is carried out in a vacuum arc melting furnace, the current during the smelting process is 200 A, the voltage is 30 V, and the smelting time is 15 s; the mass ratio of yttrium, titanium, praseodymium and silicon in the Si-Y-Ti-Pr brazing ingot is 5.44:5.44:5.44:83.57.

[0048] The Si-Y-Ti-Pr solder ingot is processed into a flake shape to obtain a flake solder.

[0049] Comparative Example 1

[0050] Silicon blocks and yttrium blocks are used as raw materials for smelting to obtain Si-Y solder ingots; wherein the smelting is carried out in a vacuum arc melting furnace, the current during the smelting process is 200A, the voltage is 30V, and the smelting time is 15s; the mass ratio of silicon element to yttrium element in the Si-Y solder ingot is 82:18.

[0051] The Si-Y solder ingot is processed into a flake shape to obtain a flake solder.

[0052] Application Example 1

[0053] A1. Place a sheet solder between two silicon carbide parts to be connected to form a sandwich structure of a component to be connected; the sheet solder is the sheet solder prepared in Example 1.

[0054] A2. Under vacuum conditions, the components to be connected are heated to 800°C at a heating rate of 10°C / min, kept warm for 10 minutes, and then heated to the sintering temperature at a heating rate of 5°C / min, kept warm for 15 minutes to obtain a silicon carbide connector; wherein the sintering temperature is 1260°C.

[0055] Application Example 2

[0056] The difference from Application Example 1 is that in step A2, the sintering temperature is 1280°C.

[0057] Comparative application example 1

[0058] The difference from Application Example 1 is that in step A1, the sheet solder is the sheet solder prepared in Comparative Example 1. It was found through experiments that the two reaction-sintered silicon carbides in Comparative Application Example 1 were not successfully connected due to the low sintering temperature.

[0059] Comparative Application Example 2

[0060] The difference from Comparative Application Example 1 is that in step A2, the sintering temperature is 1300°C.

[0061] Experimental example

[0062] The solder prepared in Example 1 was subjected to scanning electron microscopy and energy spectrum analysis, and the results are shown in Figure 1 and Figure 2 ,from Figure 1 and Figure 2 It can be seen that the yttrium, titanium, praseodymium and silicon elements are evenly distributed in the brazing material prepared in Example 1. Figure 2 In the figure, the upper left picture is the distribution diagram of silicon element, the upper right picture is the distribution diagram of titanium element, the lower left picture is the distribution diagram of praseodymium element, and the lower right picture is the distribution diagram of yttrium element.

[0063] The thermal expansion coefficient and melting point of the solder prepared in Example 1 and Comparative Example 1 were tested, and the results are shown in Table 1. It can be seen from Table 1 that compared with Comparative Example 1, the melting point of the solder prepared in Example 1 is lower. When it is used for silicon carbide brazing, the connection of silicon carbide can be achieved at a relatively low temperature (1260°C to 1280°C); compared with Comparative Example 1, the thermal expansion coefficient of the solder prepared in Example 1 is lower, and the thermal expansion coefficient is closer to the thermal expansion coefficient of silicon carbide.

[0064] Table 1

[0065]

[0066] The welds of the silicon carbide connectors prepared in Example 1 and Example 2 were analyzed by scanning electron microscope. Figure 3 and Figure 4 ,from Figure 3 and Figure 4 It can be seen that the welded joints of the silicon carbide connectors prepared in Application Example 1 and Application Example 2 are continuous, free of defects such as pores and cracks, and a good diffusion layer is formed between the brazing material and the SiC base material. The shear strength of the welded joints of the silicon carbide connectors prepared in the corresponding application example 1, application example 2, and comparative application example 2 was tested, and the results are shown in Table 2. It can be seen from Table 2 that compared with comparative application example 2, the shear strength of the welded joints of the silicon carbide connectors prepared in application example 1 and application example 2 is higher. It can be seen that compared with comparative application example 2, silicon carbide connectors with higher welded joint strength are prepared in application example 1 and application example 2 at a lower sintering temperature.

[0067] Table 2

[0068] Sample No. Shear strength(MPa) Application Example 1 35 Application Example 2 42 Comparative Application Example 2 31

[0069] The silicon carbide connector prepared in Application Example 1 was kept at 800°C for 10 hours in an atmosphere and then tested by scanning electron microscopy. Figure 5 and Figure 6 ,from Figure 5 and Figure 6 It can be seen that after being kept at 800°C for 10 hours in an atmospheric atmosphere, no oxidation enrichment occurs at the weld of the silicon carbide connector, indicating that the welded joint of the silicon carbide connector prepared in Application Example 1 has high oxidation resistance.

[0070] It should be noted that Figure 5 The cross section indicated by the middle arrow is the contact surface between the silicon carbide connector and the external oxidizing environment during the process of being kept at 800°C in an atmosphere for 10 hours.

[0071] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a brazing material for silicon carbide connection, characterized in that: include: Step S1, smelting silicon, metal yttrium, metal titanium and metal praseodymium as raw materials to obtain a Si-Y-Ti-Pr brazing ingot; the mass ratio of yttrium element, titanium element, praseodymium element and silicon element in the Si-Y-Ti-Pr brazing ingot is (5.4 to 5.5): (5.4 to 5.5): (5.4 to 5.5): (83.5 to 83.6); Step S2, processing the Si-Y-Ti-Pr solder ingot into powder or flakes to obtain a solder for silicon carbide connection.

2. The method for preparing the brazing filler metal for silicon carbide connection according to claim 1, characterized in that: In the step S1, the mass ratio of yttrium, titanium, praseodymium and silicon in the Si-Y-Ti-Pr solder ingot is 5.44:5.44:5.44:83.

57.

3. The method for preparing the brazing filler metal for silicon carbide connection according to claim 1, characterized in that: In the step S1, the smelting is carried out in a vacuum or protective atmosphere, the current during the smelting process is 200A, and the voltage is 30V to 45V.

4. The method for preparing the brazing filler metal for silicon carbide connection according to claim 1, characterized in that: In the step S1, the smelting time is 15s to 30s.

5. A brazing material for silicon carbide connection, characterized in that: The brazing material for silicon carbide connection is prepared by the method for preparing the brazing material for silicon carbide connection according to any one of claims 1 to 4.

6. A method for connecting silicon carbide, characterized in that: include: Step M1, placing the silicon carbide connection brazing material as claimed in claim 5 between two silicon carbide parts to be connected to form a sandwich structure of the components to be connected; Step M2: Under vacuum conditions, the components to be connected are heated to 1260° C. to 1280° C., and sintered at 1260° C. to 1280° C. to obtain silicon carbide connectors.

7. The method for connecting silicon carbide according to claim 6, characterized in that: In the step M1, the silicon carbide connection brazing material is in the form of a sheet.

8. The method for connecting silicon carbide according to claim 7, characterized in that: The thickness of the silicon carbide connection brazing material in the components to be connected is 0.5 mm to 1 mm.

9. The method for connecting silicon carbide according to claim 6, characterized in that: In the step M2, heating the components to be connected to 1260°C to 1280°C includes: heating the components to be connected to 800°C at a heating rate of 10°C / min to 20°C / min, keeping the temperature for 10 minutes, and heating the components to 1260°C to 1280°C at a heating rate of 5°C / min to 10°C / min.

10. The method for connecting silicon carbide according to claim 6, characterized in that: In the step M2, the sintering treatment time is 10 minutes to 30 minutes.

Images